MTR and homocystinuria: Proband AB161 displayed two other inherited rare genic CNVs: a maternal deletion of 3 genes on chr16p13.3, and a paternal duplication on chromosome 1q43 including two genes: ACTN2 and MTR. Interestingly, the MTR gene is another FMRP target gene and it has been implicated in methylcobalamin deficiency type G (MIM:250940), an autosomal recessive inherited disease that causes mental retardation, macrocytic anemia, and homocystinuria.